"Katie's depth of experience, her intellectual curiosity, and her charisma make her the perfect choice to anchor Yahoo News and the whole Yahoo Network. Her unmatched energy, savvy, and versatility enables her to connect with audiences across the globe," Mayer said in a statement. "News is a definitive daily habit for our users -- and Katie will work with our talented editorial team to pioneer a new chapter of digital journalism."

Couric, a former co-anchor of NBC's Today show and the first female anchor of the CBS Evening News, has been working as a special correspondent for ABC and hosting the syndicated daytime talk show Katie. Couric will continue to host the show after joining Yahoo.

"It's very exciting to be a part of a leading company at the intersection of content and technology,"Couric said in a statement. "I have great admiration for Marissa Mayer and her team and their commitment to bringing news, entertainment and information to the Yahoo community across multiple platforms. Joining Yahoo offers a tremendous opportunity to reach people all around the world in the way that they're using and consuming media today."

Mayer has made major progress in upgrading Yahoo's fortunes since she took over in July 2012, and the company;s stock price has soared. But its core advertising business remains flat. Mayer is betting on content, with an emphasis on video, to strengthen the company's ad performance.